Utilisation of Cellulose Waste for the Production a Chemical Intermediate of Economic Interest

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Abstract

economic interest, by Tania R. Rojas-Cuellar, submitted to The University of Manchester for the degree of Doctor of Philosophy, 2014.Currently biomass is considered to be one of the main options to substitute the fossil fuels. Nevertheless, bioenergy is not the only alternative use for organic waste materials. In recent years, the utilisation of cellulolytic waste from industries, such as the paper industry and agriculture (in fields and in processing plants), is considered to be a good source of renewable carbon to produce chemical intermediates, such as glucose, lactic acid, ethanol and acetic acid, which can be returned to the productive chain. However, the principal obstacle in the use of this material for enzymatic degradation lies in the nature of the cellulose polymer. There are still many engineering, technological and chemistry related issues which remain to be resolved.The main objective of this study is to enable the production of glucose from the enzymatic hydrolysis of cellulose waste, arising from the waste of a recycle paper plant (paper crumb) by using Trichoderma reesei strain directly, instead of the commonly used mixture enzymes. This procedure, known as the single-step glucose production process, aims to reduce the costs associated in the use of pure enzymes and pre-treatments that are usually necessary to carry out the enzymatic degradation. The paper crumb is high in cellulose fibres (32%) with an alkaline characteristic, which carries a wide variety of impurities. This study recommends using existing knowledge with regards the enzymatic activity of the fungus and demonstrates its ability to degrade this substrate; regardless of the complex matrix linked to the cellulose polymer. Due to the nature of paper crumb a number of issues had to be solved during the development of the single-step production process. Firstly, the identification of an analytical method to monitor the enzymatic degradation of the paper crumb without interference of the inorganic compounds present in the substrate. The glucose analyser GL6 proved to be most suitable in this study. Secondly; the verification of the fungus’ ability to grow in this substrate by using PDA/Paper crumb plate, which allowed its adaptation gradually and reduced the time to produce enzymes. Finally, the evaluation of the enzymatic activity under acid and alkaline conditions was undertaken. It is demonstrated that the single-step process is feasible under acid conditions. The study also found that the fermentation time was the key parameter (up to 9 h.) to avoid the consumption of the glucose. The results show that the single-step process produces the same amount of glucose as the multi-step process (0.4 g/l), however the lower glucose production making it less economically attractive and less feasible to be expanded into an industrial scale. Nevertheless, the findings of this research contribute to establishing the basics for the optimisation of the glucose production process as an alternative for cellulose waste management. This adds economic value to the organic waste minimisation, which will lead to reduce cost in production processes.

Layman's Abstract

economic interest, by Tania R. Rojas-Cuellar, submitted to The University of Manchester for the degree of Doctor of Philosophy, 2014.Currently biomass is considered to be one of the main options to substitute the fossil fuels. Nevertheless, bioenergy is not the only alternative use for organic waste materials. In recent years, the utilisation of cellulolytic waste from industries, such as the paper industry and agriculture (in fields and in processing plants), is considered to be a good source of renewable carbon to produce chemical intermediates, such as glucose, lactic acid, ethanol and acetic acid, which can be returned to the productive chain. However, the principal obstacle in the use of this material for enzymatic degradation lies in the nature of the cellulose polymer. There are still many engineering, technological and chemistry related issues which remain to be resolved.The main objective of this study is to enable the production of glucose from the enzymatic hydrolysis of cellulose waste, arising from the waste of a recycle paper plant (paper crumb) by using Trichoderma reesei strain directly, instead of the commonly used mixture enzymes. This procedure, known as the single-step glucose production process, aims to reduce the costs associated in the use of pure enzymes and pre-treatments that are usually necessary to carry out the enzymatic degradation. The paper crumb is high in cellulose fibres (32%) with an alkaline characteristic, which carries a wide variety of impurities. This study recommends using existing knowledge with regards the enzymatic activity of the fungus and demonstrates its ability to degrade this substrate; regardless of the complex matrix linked to the cellulose polymer. Due to the nature of paper crumb a number of issues had to be solved during the development of the single-step production process. Firstly, the identification of an analytical method to monitor the enzymatic degradation of the paper crumb without interference of the inorganic compounds present in the substrate. The glucose analyser GL6 proved to be most suitable in this study. Secondly; the verification of the fungus’ ability to grow in this substrate by using PDA/Paper crumb plate, which allowed its adaptation gradually and reduced the time to produce enzymes. Finally, the evaluation of the enzymatic activity under acid and alkaline conditions was undertaken. It is demonstrated that the single-step process is feasible under acid conditions. The study also found that the fermentation time was the key parameter (up to 9 h.) to avoid the consumption of the glucose. The results show that the single-step process produces the same amount of glucose as the multi-step process (0.4 g/l), however the lower glucose production making it less economically attractive and less feasible to be expanded into an industrial scale. Nevertheless, the findings of this research contribute to establishing the basics for the optimisation of the glucose production process as an alternative for cellulose waste management. This adds economic value to the organic waste minimisation, which will lead to reduce cost in production processes.

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Cellulase

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